.\" $OpenBSD: ASN1_mbstring_copy.3,v 1.6 2022/02/21 00:22:03 jsg Exp $
.\"
.\" Copyright (c) 2021 Ingo Schwarze <schwarze@openbsd.org>
.\"
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.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
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.Dd $Mdocdate: February 21 2022 $
.Dt ASN1_MBSTRING_COPY 3
.Os
.Sh NAME
.Nm ASN1_mbstring_copy ,
.Nm ASN1_mbstring_ncopy ,
.Nm ASN1_STRING_set_by_NID ,
.Nm ASN1_STRING_set_default_mask ,
.Nm ASN1_STRING_set_default_mask_asc ,
.Nm ASN1_STRING_get_default_mask ,
.Nm ASN1_tag2bit
.Nd copy a multibyte string into an ASN.1 string object
.Sh SYNOPSIS
.In openssl/asn1.h
.Ft int
.Fo ASN1_mbstring_copy
.Fa "ASN1_STRING **out"
.Fa "const unsigned char *in"
.Fa "int inbytes"
.Fa "int inform"
.Fa "unsigned long mask"
.Fc
.Ft int
.Fo ASN1_mbstring_ncopy
.Fa "ASN1_STRING **out"
.Fa "const unsigned char *in"
.Fa "int inbytes"
.Fa "int inform"
.Fa "unsigned long mask"
.Fa "long minchars"
.Fa "long maxchars"
.Fc
.Ft ASN1_STRING *
.Fo ASN1_STRING_set_by_NID
.Fa "ASN1_STRING **out"
.Fa "const unsigned char *in"
.Fa "int inbytes"
.Fa "int inform"
.Fa "int nid"
.Fc
.Ft void
.Fo ASN1_STRING_set_default_mask
.Fa "unsigned long mask"
.Fc
.Ft int
.Fo ASN1_STRING_set_default_mask_asc
.Fa "const char *maskname"
.Fc
.Ft unsigned long
.Fn ASN1_STRING_get_default_mask void
.Ft unsigned long
.Fn ASN1_tag2bit "int tag"
.Sh DESCRIPTION
.Fn ASN1_mbstring_copy
interprets
.Fa inbytes
bytes starting at
.Fa in
as a multibyte string and copies it to
.Pf * Fa out ,
optionally changing the encoding.
If the
.Fa inbytes
argument is negative, the
.Xr strlen 3
of
.Fa in
is used instead.
.Pp
The
.Fa inform
argument specifies the character encoding of
.Fa in :
.Bl -column MBSTRING_UNIV encoding
.It Ar inform Ta encoding
.It Dv MBSTRING_ASC Ta ISO-Latin-1
.It Dv MBSTRING_BMP Ta UTF-16
.It Dv MBSTRING_UNIV Ta UTF-32
.It Dv MBSTRING_UTF8 Ta UTF-8
.El
.Pp
The bit
.Fa mask
specifies a set of ASN.1 string types
that the user is willing to accept:
.Bl -column B_ASN1_UNIVERSALSTRING ASN1_UNIVERSALSTRING default
.It bit in Fa mask            Ta acceptable output type  Ta default
.It Dv B_ASN1_PRINTABLESTRING Ta Vt ASN1_PRINTABLESTRING Ta yes
.It Dv B_ASN1_IA5STRING       Ta Vt ASN1_IA5STRING       Ta no
.It Dv B_ASN1_T61STRING       Ta Vt ASN1_T61STRING       Ta yes
.It Dv B_ASN1_BMPSTRING       Ta Vt ASN1_BMPSTRING       Ta yes
.It Dv B_ASN1_UNIVERSALSTRING Ta Vt ASN1_UNIVERSALSTRING Ta no
.It any other bit             Ta Vt ASN1_UTF8STRING      Ta yes
.El
.Pp
The first type from the above table that is included in the
.Fa mask
argument and that can represent
.Fa in
is used as the output type.
The
.Dq default
column indicates whether the type is considered acceptable if the
.Fa mask
argument has the special value 0.
.Pp
The following bit mask constants
each include several of the bits listed above:
.Bl -column B_ASN1_DIRECTORYSTRING_ MMM MMM MMM MMM MMM MMMM
.It mask constant             Ta PRI Ta IA5 Ta T61 Ta BMP Ta UNI Ta UTF8
.It Dv B_ASN1_DIRECTORYSTRING Ta yes Ta no  Ta yes Ta yes Ta yes Ta yes
.It Dv DIRSTRING_TYPE         Ta yes Ta no  Ta yes Ta yes Ta no  Ta yes
.It Dv PKCS9STRING_TYPE       Ta yes Ta yes Ta yes Ta yes Ta no  Ta yes
.El
.Pp
If
.Fa out
is
.Dv NULL ,
.Fa inform ,
.Fa inbytes ,
and
.Fa in
are validated and the output type is determined and returned,
but nothing is copied.
.Pp
Otherwise, if
.Pf * Fa out
is
.Dv NULL ,
a new output object of the output type is allocated
and a pointer to it is stored in
.Pf * Fa out .
.Pp
Otherwise,
.Pf ** Fa out
is used as the output object.
Any data already stored in it is freed
and its type is changed to the output type.
.Pp
Finally,
.Fa in
is copied to the output object, changing the character encoding if
.Fa inform
does not match the encoding used by the output type.
.Pp
.Fn ASN1_mbstring_ncopy
is similar except that the number of characters in
.Fa in
is restricted to the range from
.Fa minchars
to
.Fa maxchars ,
inclusive.
If
.Fa maxchars
is 0, no upper limit is enforced on the number of characters.
.Pp
.Fn ASN1_STRING_set_by_NID
is similar with the following differences:
.Bl -bullet -width 1n
.It
If
.Fa out
is
.Dv NULL ,
a new output object is allocated and returned
instead of skipping the copying.
.It
If
.Fa nid
has a global string table entry that can be retrieved with
.Xr ASN1_STRING_TABLE_get 3 ,
.Fa mask ,
.Fa minchars ,
and
.Fa maxchars
are taken from that string table entry.
For some values of
.Fa nid ,
an additional global mask is AND'ed into the mask before using it.
The default value of the global mask is
.Dv B_ASN1_UTF8STRING .
.It
If
.Fa nid
has no global string table entry,
.Dv B_ASN1_PRINTABLESTRING | B_ASN1_T61STRING |
.Dv B_ASN1_BMPSTRING | B_ASN1_UTF8STRING
is used instead of the mask taken from the table,
and the global mask is also AND'ed into it.
.It
Even though success and failure happen in the same situations,
the return value is different.
.Xr ASN1_STRING_type 3
can be used to determine the type of the return value.
.El
.Pp
.Fn ASN1_STRING_set_default_mask
sets the global mask used by
.Fn ASN1_STRING_set_by_NID
to the
.Fa mask
argument.
.Pp
.Fn ASN1_STRING_set_default_mask_asc
sets the global mask as follows:
.Bl -column utf8only
.It Ar maskname    Ta Ar mask
.It Qo default  Qc Ta anything
.It Qo nombstr  Qc Ta anything except Dv B_ASN1_BMPSTRING | B_ASN1_UTF8STRING
.It Qo pkix     Qc Ta anything except Dv B_ASN1_T61STRING
.It Qo utf8only Qc Ta Dv B_ASN1_UTF8STRING
.El
.Pp
If the
.Fa maskname
argument starts with the substring
.Qq MASK:\& ,
the rest of it is interpreted as an
.Vt unsigned long
value using
.Xr strtoul 3 .
.Pp
.Fn ASN1_tag2bit
translates ASN.1 data types to type bits as follows:
.Bl -column V_ASN1_OBJECT_DESCRIPTOR B_ASN1_UNIVERSALSTRING
.It Fa tag                      Ta return value
.It Dv V_ASN1_BIT_STRING        Ta Dv B_ASN1_BIT_STRING
.It Dv V_ASN1_BMPSTRING         Ta Dv B_ASN1_BMPSTRING
.It Dv V_ASN1_BOOLEAN           Ta 0
.It Dv V_ASN1_ENUMERATED        Ta Dv B_ASN1_UNKNOWN
.It Dv V_ASN1_EOC               Ta 0
.It Dv V_ASN1_EXTERNAL          Ta Dv B_ASN1_UNKNOWN
.It Dv V_ASN1_GENERALIZEDTIME   Ta Dv B_ASN1_GENERALIZEDTIME
.It Dv V_ASN1_GENERALSTRING     Ta Dv B_ASN1_GENERALSTRING
.It Dv V_ASN1_GRAPHICSTRING     Ta Dv B_ASN1_GRAPHICSTRING
.It Dv V_ASN1_IA5STRING         Ta Dv B_ASN1_IA5STRING
.It Dv V_ASN1_INTEGER           Ta 0
.It Dv V_ASN1_ISO64STRING       Ta Dv B_ASN1_ISO64STRING
.It Dv V_ASN1_NULL              Ta 0
.It Dv V_ASN1_NUMERICSTRING     Ta Dv B_ASN1_NUMERICSTRING
.It Dv V_ASN1_OBJECT            Ta 0
.It Dv V_ASN1_OBJECT_DESCRIPTOR Ta Dv B_ASN1_UNKNOWN
.It Dv V_ASN1_OCTET_STRING      Ta Dv B_ASN1_OCTET_STRING
.It Dv V_ASN1_PRINTABLESTRING   Ta Dv B_ASN1_PRINTABLESTRING
.It Dv V_ASN1_REAL              Ta Dv B_ASN1_UNKNOWN
.It Dv V_ASN1_SEQUENCE          Ta Dv B_ASN1_SEQUENCE
.It Dv V_ASN1_SET               Ta 0
.It Dv V_ASN1_T61STRING         Ta Dv B_ASN1_T61STRING
.It Dv V_ASN1_TELETEXSTRING     Ta Dv B_ASN1_TELETEXSTRING
.It Dv V_ASN1_UNDEF             Ta 0
.It Dv V_ASN1_UNIVERSALSTRING   Ta Dv B_ASN1_UNIVERSALSTRING
.It Dv V_ASN1_UTCTIME           Ta Dv B_ASN1_UTCTIME
.It Dv V_ASN1_UTF8STRING        Ta Dv B_ASN1_UTF8STRING
.It Dv V_ASN1_VIDEOTEXSTRING    Ta Dv B_ASN1_VIDEOTEXSTRING
.It Dv V_ASN1_VISIBLESTRING     Ta Dv B_ASN1_VISIBLESTRING
.It 11, 13, 14, 15, 29          Ta Dv B_ASN1_UNKNOWN
.It Dv other Po < 0, > 30 Pc    Ta Dv 0
.El
.Pp
In typical usage, the calling code calculates the bitwise AND
of the return value and a mask describing data types
that the calling code is willing to use.
If the result of the AND operation is non-zero, the data type is
adequate; otherwise, the calling code may need to raise an error.
.Sh RETURN VALUES
.Fn ASN1_mbstring_copy
and
.Fn ASN1_mbstring_ncopy
return the
.Dv V_ASN1_*
constant representing the output type or \-1 if
.Fa inform
is invalid, if
.Fa inbytes
or
.Fa in
is invalid for the
.Fa inform
encoding, if
.Fa in
contains an UTF-16 surrogate,
which is unsupported even for input using the UTF-16 encoding,
or if memory allocation fails.
.Pp
.Fn ASN1_mbstring_ncopy
also returns \-1 if
.Fa in
contains fewer than
.Fa minchars
or more than
.Fa maxchars
characters.
.Pp
.Fn ASN1_STRING_set_by_NID
returns the new or changed ASN.1 string object or
.Dv NULL
on failure.
.Pp
.Fn ASN1_STRING_set_default_mask_asc
returns 1 if successful or 0 if
.Qq MASK:\&
is not followed by a number, if the number is followed by a non-numeric
character, or if the
.Fa maskname
is invalid.
.Pp
.Fn ASN1_STRING_get_default_mask
returns the global mask.
.Pp
.Fn ASN1_tag2bit
returns a
.Dv B_ASN1_*
constant or 0.
.Sh SEE ALSO
.Xr ASN1_PRINTABLE_type 3 ,
.Xr ASN1_STRING_new 3 ,
.Xr ASN1_STRING_set 3 ,
.Xr ASN1_STRING_TABLE_get 3 ,
.Xr ASN1_UNIVERSALSTRING_to_string 3
.Sh HISTORY
.Fn ASN1_mbstring_copy ,
.Fn ASN1_mbstring_ncopy ,
.Fn ASN1_STRING_set_by_NID ,
.Fn ASN1_STRING_set_default_mask ,
.Fn ASN1_STRING_set_default_mask_asc ,
and
.Fn ASN1_STRING_get_default_mask
first appeared in OpenSSL 0.9.5 and have been available since
.Ox 2.7 .
.Pp
.Fn ASN1_tag2bit
first appeared in OpenSSL 0.9.7 and has been available since
.Ox 3.2 .
.Sh BUGS
If integer overflow occurs in
.Fn ASN1_STRING_set_default_mask_asc
while parsing a number following
.Qq MASK:\& ,
the function succeeds, essentially behaving in the same way as for
.Qq default .
.Pp
Passing
.Qq default
to
.Fn ASN1_STRING_set_default_mask_asc
does
.Em not
restore the default mask.
Instead, passing
.Qq utf8only
does that.
